1. Field of the Invention
The present invention relates to a color correction apparatus which is used in an imaging apparatus to make compensation for color difference from apparatus to apparatus.
2. Description of the Related Art
In video cameras for use in broadcast stations, it is required that the color characteristics of each video camera be precisely adjusted. However, in imaging apparatus such as video cameras for use in broadcast stations, a difference in the output image can occur among cameras due to slight variations in spectral characteristics of color filters or color separation prisms disposed in front of an image sensor device such as a CCD (charge coupled device). To avoid the above problem, the inventors of the present invention have proposed a technique of making color adjustment for each video camera using a linear matrix camera which is generally disposed in the video camera for use in broadcast stations. The linear matrix circuit serves to electronically compensate for an error in the color of the reproduced image caused by the difference in the spectral characteristic between the video camera and the ideal spectral characteristic for example according to the NTSC standard. In this technique of compensating for the color difference among video cameras using the linear matrix circuit, the same colors for example colors of a color chart are measured by two different imaging apparatus, and the coefficients of the linear matrix circuit are determined by means of calculation based on the data of the colors so that the differences in the colors between the two imaging apparatus are minimized. The resultant coefficients are given to the linear matrix circuit. Hereinafter, this process is referred to as a color setup process.
However, in the technique of compensating for the color differences by determining the coefficients of the linear matrix circuit on the basis of the measurement of particular colors so that the color differences are minimized, although it is possible to adjust a few colors to nearly ideal colors, it is difficult to perfectly eliminate color differences among cameras for all colors. When a user is not satisfied with the result of the color setup process, it is required to manually make color adjustment to obtain better consistency. However, such a manual adjustment requires a very tedious and complicated procedure. Such the manual color adjustment is performed for example when it is desirable that a particular color such as a flesh color be adjusted precisely, or when a color a user desires to adjust precisely is not found in the color chart. In general, the flesh color is frequently specified as a color to be adjusted precisely. However, the standard of the flesh color varies from a broadcast station to another around the world, and therefore the adjustment of the flesh color which is not included in the color chart is generally performed manually, spending a long time.
In view of the above problems, it is an object of the present invention to provide a color correction apparatus for use in an imaging apparatus, capable of adjusting arbitrary desired colors so as to minimize the color differences from an imaging apparatus to another by means of simple operations.